A bolometer, which changes its resistance in response to optical heating, is often used in the art to detect the intensity of incident infrared (IR) radiation or to capture multi-pixel IR images of incident IR radiation intensity. Typically, to measure incident IR radiation, a bias (e.g., a bias voltage or current) is applied across a bolometer so that its resistance, or any change thereof, can be measured and translated into a signal indicative of the intensity of IR radiation received at the bolometer. In this regard, many conventional bolometer circuits include a significant amount of circuitry dedicated to generating and controlling the bias across bolometers at a desired level. For example, conventional bias generation and control circuits may include transistors or other control mechanisms in a bolometer conduction path, along with circuitry to drive such transistors or other control mechanisms, to generate and maintain a desired bias across bolometers in face of variations or mismatches in operating characteristics of components and changing ambient or internal conditions.
Unfortunately, such additional transistors or other control mechanisms in a bolometer conduction path not only increase the size, cost, complexity, and power consumption of conventional bolometer circuits, but also introduce noise in the sensitive bolometer conduction path. Furthermore, because such additional transistors or other control mechanisms may control the bias by limiting the current flow and/or voltage on the bolometer conduction path, the voltage and/or current available for biasing the bolometer is effectively reduced to only a portion of the supply voltage or current, which in turn reduces the sensitivity of conventional bolometer circuits. Even with such costly bias generation and control approaches, conventional bolometer circuits typically exhibit a reduced usable signal range for representing IR radiation intensity (e.g., reduced signal swing) because of the need to allow for effects on output signals due to changing ambient and internal conditions such as, for example, self-heating of bolometers (also referred to as pulsed bias heating or pulse bias heating) or other factors. Accordingly, there is a need for a high-performance bolometer circuit that generates and maintains biases across bolometers at a desired level and/or provides a large usable signal range without the cost, size, complexity, noise, and power consumption associated with conventional bolometer circuits.